1. Field of the Invention
The present invention relates to a video cassette recorder (hereinafter, referred to as "VCR"), and more particularly to a head cassette assembly for a video cassette recorder.
2. Description of the Prior Art
Generally, a video cassette recorder is an apparatus for recording image and audio signs onto a magnetic tape and for reproducing the signals from the magnetic tape on which the signals are recorded. The video cassette reorder is provided with a main base, a driving system mounted on the main base for drawing the tape from a cartridge and for running the tape around the outer surface of the head drum accord to a predetermined route, and a head drum assembly for recording the video signals onto the tape and for reproducing the video signals from the tape on which the signals are recorded.
The head drum assembly includes an upper drum having a head for recording the video signals on the tape and for reproducing the video signals from the tape on which the video signals is recorded, and a lower drum which is positioned below the upper drum and is provided with a motor for rotating the upper drum. While the upper drum is rotated by the motor, the head records the video signals onto the tape and reproduces the video signals from the tape on which the video signals are recorded.
Generally, a rotary transformer for transmitting the video signals which are recorded/reproduced onto/from the tape to art external device is arranged in the lower drum. U.S. Pat. No. 5,581,426 (issued to Keum-Mo Kim on Dec. 3, 1996, entitled "Upper Head Drum Assembly including at least one Nut Cap" and assigned to the assignee of the present application) discloses one example of a head drum assembly.
FIG. 1 illustrates a conventional head drum assembly 100 which is similar to the head drum assembly disclosed in the above U.S. patent. As illustrated in the figure, the head drum assembly 100 is provided with a lower dram 120 fixed on the main base (not shown) and an upper drum 110 mounted on the lower drum 120. The upper drum 110 has head bases 112 at a lower surface thereof, and each of the head bases 112 has a magnetic head 114 on an upper surface thereof. At the lower surface of the lower drum 120, a motor 130 for generating the rotational force is installed, and a shaft 140 which transmits the rotational force of the motor 130 to the upper drum 110 is rotatably inserted into the upper dram 110 and the lower drum 120. A rotary transformer 122 is installed between the upper drum 110 and the lower drum 120. The rotary transformer 122 is provided with a rotor 122a which is connected to the upper drum 110 and is rotated together with the upper drum 110, and a stator 122b which is fixed on an upper portion of the lower drum 120.
The upper drum 110 is fixed by joining screws 111 at a plange 117 which is provided at the shaft 140. The upper drum 110 has second screw holes 116b for controlling the level of the head base's height, and has first screw holes 118b which penetrate from an outer surface to a lower surface of the upper drum 110 for joining the head bases 112 with the upper drum 110. The head bases 112 and the rotary transformer 122 are spaced apart from each other.
The plurality of the head bases 112 are fixed at the lower surface of the upper drum 110 by screwing the joining screws 118a into first screw holes 118b, and each of the heads 114 is attached to the upper surface of each of the head bases 112. The heads 114 record the video signals onto the tape and reproduce the video signals from the tape on which the video signals are recorded while the magnetic head are rotated together with the upper drum 110. The magnetic beads 114 are arranged at the upper drum 110 by a regular interval, desirably 180.degree., for recording and reproducing the video signals onto and from the track formed on the tape. The heights of the heads 114 are controlled by fixing screws 116a and the fixing screws 116a are inserted through the second holes 116b of the upper drum 110. The rotary transformer 122 transmits the video signals from the head 114 to an external device and/or from the external device to the head 114. The rotor 122a of the rotary transformer 122 is electrically connected to the head 114 by an electric wire 115.
The video signals reproduced by the heads 114 are transmitted to the external device via the stator 122b of the rotary transformer 122 from the rotor 122a of the rotary transformer 122 by an induction between the rotor 122a of the rotary transformer 122 and the stator 122b of the rotary transformer 122. Alternatively, the rotary transformer 122 transmits the video signals which are transmitted from the external device to the head 114 via the rotor 122a of the rotary transformer 122 from the stator 122b of the rotary transformer 122 by an induction between the rotor 122a of the rotary transformer 122 and tie stator 122b of the rotary transformer 122.
Accordingly, the heads 114 are electrically connected with an external device, for example an amplifier etc, while the heads 114 rotate together with the upper drum 110. However, in the conventional head drum assembly, each of head bases 112 has to be fixed to the upper drum 110, and thus the height of each of the treads 114 should be controlled independently. Therefore, as the number of the heads 114 increases, the time required for controlling the heights of the head bases 112 and for fixing the head bases 112 to the upper drum also increases. In addition, if the number of heads 114 increase, the cost of producing the head drum assembly also increases.